I'm gonna go on a nerd rant for a minute

Making every superhero the whole "I don't kill" is lazy writing. It forces a moral superiority that feels forced. With Batman it's been added to the ethos and makes sense because he's only a hero due to tragedy

But every hero?
Mediocre writing.

Honestly, the 2 First CW hero shows did the kill vs no kill best. Green arrow vs flash

GA has a list of people who he knows are evil. Just bad evil people. He came back from 5 years of torture. Pain. And was even once trained by the Russian mafia.
He also came from a life of luxury and excess. Never needed or wanted for anything. Billionaire

Then we have Flash. A CSI whose father was falsely accused of murder. Flash solves murders and stops villains with silly names. He also knows his enemies want him to go dark side. So he has to remain opposed.

But too often in modern shows/movies/comics we see all these heroes with the no kill code. And yeah duh murder bad.
But when it's Galactus, or Apokalypse, or any of those heavy hitters...
It doesn't make sense.

You have literal gods, inter dimensional wizards, and beings that could take them on without breaking a sweat.

Some characters have a moral code as their basis. Spider-man, BatFam, SuperFam, and some others.

But then you'll tell me it's stratified to all?
What, we gonna say Ghost Rider can't kill? HES A DEMON!

In short, adding it to every hero without reason feels lazy. Give a reason, a background, something. Because otherwise it feels like
"Well they don't kill. The villain does. So hero is automatically good"

The moral philosophy behind it gets muddled. It gets messy. And it feels too easy to just add in as superiority in writing.

Especially when, in some versions, it leads to a clown nuking a city, which leads to an alien authoritarian regime

LOOKING AT YOU, INJUSTICE!

Batman's "no kill" code essentially reached fever pitch when he refused to let others stop a literal god who was assisting an alien near-god who also had the fastest man in the universe on their side.

Anyway it has to be fleshed out better and done better

/rant